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Illinois: Measure consumption before attributing savings
Start with DOE FEMP: boiler purchasing, sizing and lifecycle analysis. The table below links this decision to the represented gas companies in Illinois. It does not establish service or supplier availability for every account.
Build the operating baseline
Record actual billing periods, estimated readings, operating hours and occupancy or production. Separate space heating from process and hot-water use where the available data permits. Explain changes before comparing periods.
Reconcile engineering and procurement
Have qualified personnel evaluate controls, equipment and service capacity. Update the contracted volume forecast after a project and review tolerance or minimum-volume terms. Verify program eligibility and preapproval before treating an incentive as funded.
Illinois utility application
| Gas service company | Contract component to revisit after load reduction | Primary reference |
|---|---|---|
| Nicor Gas | Utility supply benchmark versus AGS supply and recurring fees, keeping delivery separate | Official program / tariff |
| Ameren Illinois | Applicable utility gas supply and delivery components; incremental transport costs if eligible | Official program / tariff |
| Peoples Gas | Utility supply benchmark versus AGS supply and recurring fees, keeping delivery separate | Official program / tariff |
| North Shore Gas | Utility supply benchmark versus AGS supply and recurring fees, keeping delivery separate | Official program / tariff |
| MidAmerican Energy | State-specific gas supply and delivery components | Official program / tariff |
Nicor Gas: the program detail behind this decision
The ICC identifies Nicor Gas, Peoples Gas and North Shore Gas for residential and small-commercial Gas Choice. An Alternative Gas Supplier sells supply while the delivery utility remains. The ICC’s utility list does not establish that every supplier accepts every commercial class or offers a suitable contract. Program Illinois.
Apply the evidence to an account file
After reducing forecast consumption, revisit Utility supply benchmark versus AGS supply and recurring fees, keeping delivery separate. Ask whether the revised operating load changes The named delivery company and its eligible small-commercial service class or any conditions associated with Supplier registration, cancellation terms and return-to-utility conditions.
Worked check: fixed charges do not fall with every therm
Assume hypothetical use of 10,000 therms at a constant $0.80 supply price and a $30 monthly supply fee. Modeled supply cost is $8,360. If use falls ten percent to 9,000 therms with the same price and fee, the total becomes $7,560: an $800 reduction, or about 9.57 percent of that supply total. This excludes delivery, taxes and project costs and proves no equipment result. The illustration shows why a percentage therm reduction is not automatically the same percentage dollar reduction.
Turn the review into a calculation
Build a monthly weighted budget. Enter documented assumptions in matching energy units. Keep any charge outside both supply offers separate; the result does not establish eligibility or an available quote.
Read the Illinois utility guide for the wider service-company distinctions. Convert billed gas units using the bill’s heat-content factor when moving from volume to energy.
Sources and review notes
- DOE FEMP: boiler purchasing, sizing and lifecycle analysis
- Illinois ICC Natural Gas Choice FAQ
- Midamerican Territory
Reviewed October 16, 2026. Program information can change. Confirm the effective utility tariff, supplier availability and written offer before proceeding. Examples and planning tools are educational; they are not executable quotes or verified customer results.